It is generally known that a magnetic tape cartridge is used to prevent dust from accumulating on the enclosed tape and can be generally equipped with tape reel locking means constructed to prevent the tape from unwinding off the tape reel when not in use. A tape cartridge can also provide a pivotal lid which is open to expose the tape during use and closed to protect the tape when not in use.
One known type of tape reel locking means comprises a hub locker which retractably engages saw teeth on the perimeter of the tape reel hub and is resiliently urged to engage the saw teeth by spring means connected to the interior of the upper shell of the tape cartridge. When it is desired to rotate a tape reel during play of the audio tape, the hub locker is retracted from the saw teeth. When the tape reel is not in use, the hub locker is urged into engagement with the saw teeth by the spring means, thereby preventing rotation of the tape reel and corresponding unwinding of the tape.
A hub locker generally provides extended wings which are disposed proximate sidewalls of the tape cartridge lid. When the lid is opened, structure of the lid sidewalls engages the hub locker wings, thereby pulling the hub locker out of engagement with the tape reel hub.
Referring to FIG. 3, which shows an embodiment of a typical prior art cartridge, a projection 52 is formed on the interior of each sidewall 51 of the cartridge lid 50. When the lid is open, each projection 52 pulls a hub locker wing 53 by engaging a jaw 54 of the hub locker wing 53.
Referring to FIGS. 4A and 4B, the jaw 54 and hub locker wing 53 are urged forward. This forward movement disengages the hub locker from the saw teeth of the tape reel hub.
One disadvantage of this known configuration is that the projection 52 is not reliably engaged by the jaw 54. The hub locker wing 53 can be become bent after repeated movement by the projection 52, thereby causing separation of the jaw 54 and projection 52. As a result, the hub locker is not pulled adequately, and the locked tape reel is not released during play of the tape.